U.S. patent number 7,317,275 [Application Number 10/536,479] was granted by the patent office on 2008-01-08 for harmonic propulsion and harmonic controller.
This patent grant is currently assigned to The Trustees of Columbia University in the City of New York. Invention is credited to Michael R. Treat.
United States Patent |
7,317,275 |
Treat |
January 8, 2008 |
Harmonic propulsion and harmonic controller
Abstract
A device and method for propelling objects using periodic or
harmonic vibrations is described. The device comprises a flexible
substrate or surface and a source of vibrational energy that is
applied to the substrate or surface. Specific embodiments include a
device which can move along a flat surface, which can climb a
smooth vertical or slanted wall, which can move along a ceiling
while suspended upside down, which can climb up a smooth hollow
tube, or which can move through liquids.
Inventors: |
Treat; Michael R. (New York,
NY) |
Assignee: |
The Trustees of Columbia University
in the City of New York (New York, NY)
|
Family
ID: |
37865706 |
Appl.
No.: |
10/536,479 |
Filed: |
September 30, 2004 |
PCT
Filed: |
September 30, 2004 |
PCT No.: |
PCT/US2004/032702 |
371(c)(1),(2),(4) Date: |
October 03, 2005 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20060125336 A1 |
Jun 15, 2006 |
|
Current U.S.
Class: |
310/328; 310/330;
310/323.01 |
Current CPC
Class: |
B63H
1/30 (20130101); B63H 19/00 (20130101); B60L
50/00 (20190201); H02N 2/026 (20130101); H02N
2/0065 (20130101) |
Current International
Class: |
H01L
41/09 (20060101); H02N 2/04 (20060101) |
Field of
Search: |
;310/323.01,323.02,323.03,323.16,313.17,323.18,328-332 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Schuberg; Darren
Assistant Examiner: Rosenau; Derek
Attorney, Agent or Firm: Wolf, Block, Schorr &
Solis-Cohen LLP Dippert; William H.
Claims
What is claimed is:
1. A device comprising: a flexible substrate having at least one
substantially flat surface; and at least one source of vibrational
energy attached to or in communication with at least one of the at
least one substantially flat surface to apply vibrational energy to
the flexible substrate, wherein the vibrational energy causes
periodic motion in the flexible substrate to cause the device to
adhere to an exterior surface and the device is capable of
translational motion along the exterior surface.
2. The device of claim 1, wherein the vibrational energy is
harmonic.
3. The device of claim 2, wherein the vibrational energy causes the
flexible substrate to flex in a harmonic fashion.
4. The device of claim 2, wherein at least one of the at least one
source of vibrational energy imparts vibrations to said substrate
to cause said substrate to move in a translational fashion.
5. The device of claim 1, wherein the exterior surface is other
than horizontal.
6. The device of claim 5, wherein the exterior surface is
vertical.
7. The device of claim 5, wherein the exterior surface is upside
down.
8. The device of claim 1, wherein a change in frequency of the
vibrational energy causes the direction of the motion of the device
to change.
9. The device of claim 1, wherein the flexible substrate has a
point of asymmetry.
10. The device of claim 1, wherein the flexible substrate has first
and second substantially parallel planar surfaces.
11. The device of claim 1, wherein the flexible substrate is
circular, rectangular, oval, square, or hemispherical.
12. A device capable of translational motion comprising: a flexible
substrate having at least one substantially flat surface; and at
least one source of harmonic vibration attached to or in
communication with at least one of the at least one substantially
flat surface to apply vibrational energy to the flexible substrate,
wherein the harmonic vibration causes periodic motion in the
flexible substrate to cause the device to adhere to an exterior
surface and the device is capable of translational motion along the
exterior surface.
13. The device of claim 12, wherein at least one of the at least
one source of harmonic vibration imparts vibrations to said
substrate to cause said substrate to move in a translational
fashion.
14. The device of claim 12, wherein the exterior surface is other
than horizontal.
15. The device of claim 14, wherein the exterior surface is
vertical.
16. The device of claim 14, wherein the exterior surface is upside
down.
17. The device of claim 12, wherein at least one of the at least
one source of harmonic vibration is attached to the flexible
substrate.
18. The device of claim 1 or 12 which also comprises an asymmetry
element.
19. The device of claim 18, wherein the asymmetry element comprises
bristles, spines or spicules embedded in a flexible matrix, regular
or irregular projections, fins, or a conformable mat.
20. The device of claim 19, wherein the asymmetry element comprises
bristles.
21. The device of claim 12, wherein the flexible substrate has
first and second substantially parallel planar surfaces.
22. The device of claim 12, wherein the flexible substrate is
circular, rectangular, oval, square, or hemispherical.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon co-pending, commonly assigned U.S.
provisional patent application Ser. No. 60/507,667, filed Sep. 30,
2003, which is incorporated herein in its entirety.
FIELD OF THE INVENTION
The present invention generally relates to a method for moving
objects. The present invention specifically is directed to
propelling objects by using periodic or harmonic vibrations.
Embodiments of the present invention include a method to move an
object along a flat surface (translating horizontally), to move an
object up a smooth vertical wall (climbing vertically), to move an
object along a ceiling while the object is upside down relative to
its position in normal horizontal translation, to climb inside a
smooth hollow tube, to swim through liquids, and to rotate. The
present invention is also directed to devices which execute the
various movements.
BACKGROUND OF THE INVENTION
Historically, the usual means for propelling objects along the
ground has been by employing wheels. Typically at least one wheel
is made to move by means of a motor. The wheel so driven exerts
force on the ground as it turns, and the object to which the wheel
is attached will move forward. A common example of such a method is
that of propulsion of automobiles. Another means for propelling or
moving objects is a propeller. A propeller will push against a
fluid in which an object is immersed and thereby propel the object
forward. Simple examples would be the motion of an airplane
propeller against the fluid air or the motion of a boat propeller
against the fluid water. A different means of propulsion is
inertial reaction in which mass is expelled in one direction,
causing an object expelling the mass to move in the opposite
direction, by virtue of conservation of linear momentum. A simple
example of such motion would be the motion of a rocket or a jet
airplane.
Although there are numerous examples of the use of wheels,
propellers, and reaction engines to impart translation motion,
there appear to be relatively few examples of the use of vibrations
to induce motion. Of the few vibratory examples, most involve the
use of vibrations imparted to the entire surface on which the
moving object is travelling. One such example is the use of
vibratory conveyor belts to move grain or small parts in
manufacturing operations. There is also a toy sports game in which
miniature football players are moved along a playing field, which
is a sheet of metal, by vibrations to the entire playing field
induced by an electromechanical motor (such as a buzzer). However,
there are no devices wherein there is a self-contained and mobile
source of vibrations that cause an object to move translationally
in a directable manner.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a method and device for
harmonic propulsion.
It is also an object of the invention to provide a method and
device for propelling and/or controlling objects by use of periodic
or harmonic vibrations.
It is a further object of the invention to provide a method and
device for imparting translational motion to an object.
It is a yet further object of the invention to provide a method and
device for imparting translational motion to an object on a surface
by vibrating the object to produce harmonic motion and coupling the
vibration to the surface in an asymmetric way
It is a yet further object of the invention to provide a method and
device to move an object along a flat surface, to move an object up
a vertical wall, to move an object along a ceiling, to move an
object through a smooth hollow tube, to move an object through a
liquid or fluid, or to cause an object to rotate.
These and other objects of the invention will become more apparent
from the discussion below.
SUMMARY OF THE INVENTION
According to one aspect of the invention, vibratory motion is used
to perform the functions of devices described herein, namely, to
move along a level surface, to climb up a smooth vertical or
slanted wall, to move upside down on a ceiling, or to climb up a
hollow tube. Another aspect of the invention comprises a solution
to the problem of controlling the direction of such moving devices.
Without directional control, the utility of a moving device is much
reduced; and, with directional control, the method and device for
which is taught by the present invention, it becomes possible to
build devices which can be used for exploration of intricate
spaces, under either remote control or control based on an on-board
set of sensors and decision-making circuits. A device according to
the invention is expected to be have various applications. One
potential use is in the in the medical field, for example, in or
with a partly or wholly self-propelled endoscope or other invasive
medical device.
A great advantage of vibratory or harmonic propulsion is that such
devices may be very small and simple compared to more conventional
devices, such as wheeled devices. This is because this form of
propulsion does not require axles, bearings, transmissions, or even
wheels, as are needed for wheeled devices. This form of propulsion
does not require propellers or jet engines. The present invention
requires a system with a source of vibrations and a driving
surface, which comes in contact with the surface upon which the
device is moving.
Also, unlike wheels or treads (as in a tank), harmonic propulsion
can be effected on any or all surfaces of the device, instead of
being limited to the aspects of the device (the driving surface of
the wheels or treads). Therefore, it becomes very easy using
harmonic propulsion to build devices which can, for example, ascend
the inside of hollow pipes since the device can obtain propulsion
from the entire circumference of the pipe. Also, the surface of
vibration can be adjusted as to its stiffness and texture so that
the device can move on a great variety of terrain (for example,
hard, smooth, dry ground versus softer wet ground). In one
embodiment, it is envisioned that this technology will allow for
the development of a practical self-propelled endoscope to explore
a patient's gastrointestinal tract or another corporeal channel or
site.
In its simplicity and with few moving parts, the present invention
overcomes the problems of the prior art. The present invention
describes a device and method to cause an object to move
translationally by impartation of vibrational energy.
One embodiment of the invention is generally directed to imparting
translational motion of an object by application of vibrations,
preferably harmonic vibrations.
Another embodiment of the invention is a device to effect
translational motion that comprises a source of harmonic or
periodic mechanical or acoustic vibrations, a vibrating surface
whose modes of vibration are excited by the source of vibrations,
and a symmetry breaking element.
Another embodiment of the invention concerns a method to effect
translational motional comprising the steps of applying harmonic or
periodic vibration to an object, exciting modes of vibration in a
surface, and directing the translational motion of the object by
using symmetry breaking elements. The present invention
specifically discloses types of vibration sources, types of
vibrating surfaces, and types of antisymmetry elements.
Other embodiments of the present invention include methods to
effect translational motion from traveling waves, translational
motion from standing waves, wall climbing motion, directional
control using vibrating surfaces ("focusing surfaces") which
interact with obstacles, and directional control using
eigenmodes.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of one embodiment of the invention;
FIG. 2 is a perspective view of an embodiment of the invention on a
vertical surface; and
FIG. 3 is a schematic cross-sectional view of an embodiment of the
invention having a distinct antisymmetry element.
DETAILED DESCRIPTION OF THE INVENTION
In general, the present invention represents a novel approach to
effect translational motion by application of vibrations. More
particularly, aspects of the invention are directed to a device to
effect such motion and a method to produce such motion.
A device according to the invention employs vibratory motion
emanating from the device itself, to effect translational motion.
Such a device comprises a source of harmonic or periodic mechanical
or acoustic vibrations. This vibration source must be energetic
enough to produce amplitudes of vibration which can actually cause
movement of the device. Suitable vibration sources include, for
example, the following:
(1) an electric motor which is fitted with an eccentric cam. A
preferred aspect of a motor which rotates an eccentric weighted cam
is that traveling waves can be produced, since the motor-cam
combination tends to produce a rotating or twisting motion in
addition to an up-down and side to side motion;
(2) an electromechanical buzzer consisting of an electromagnet and
a springy steel vibrating reed. Such devices are preferred for
producing standing waves;
(3) an electromagnetic audio speaker;
(4) a piezoelectric speaker or bending element; and
(5) a gas under pressure escaping from a nozzle, which is used to
vibrate a reed or drive some sort of oscillating device such as a
piston-cylinder combination. If the source of the gas is some sort
of combustion process, then it is possible to obtain a much greater
power to weight ratio than is possible with battery powered motors.
Another method of obtaining gas under pressure would be to exploit
a phase change of a particular substance, e.g., the change of solid
CO.sub.2 ("dry ice") into a gas at room temperature. Yet another
means of obtaining a gas under pressure would be some sort of
chemical reaction, e.g., the breakdown of acetic acid and sodium
bicarbonate into CO.sub.2 (gas) and water.
A device according to the invention comprises a vibratable or
vibrating substrate whose modes of vibration are excited by the
source of vibrations. The vibrating substrate needs the correct
stiffness (modulus of elasticity) and mass density to vibrate. It
will also need to have the correct size and shape so that its
normal modes of vibration can result in forward, left, and right
motion of the device. Size and shape of the device are selected to
optimize outcome. Typical shapes include circular, rectangular,
oval, and square, circular being preferred. It has been found
empirically that plates with these shapes have normal modes of
vibration which lend themselves to forward motion with the ability
to be directed to the right or to the left as desired. Some
particular embodiments are a thin plastic sheet, a thin brass
sheet, and a thin Styrofoam sheet, having a thickness from about
0.02 to about 0.20 inches thick, preferably from about 0.05 to
about 0.15 inches thick. In a preferred embodiment of the invention
the sustrate will be flat or substantially flat where the surface
of the substrate facing a horizontal, slanted, or vertical surface
may have a slightly angled outer periphery or "lip", which will
extend all, or substantially all, the way around the outer
periphery of the substrate.
Preferably a device according to the invention comprises an
"antisymmetry element" (or symmetry breaking element) which will
break the symmetry of the vibrating motion relative to the ground
and thereby produce a net translational movement. This antisymmetry
element can be an arrangement of projections or bristles situated
at an angle to the vibrating surface which functions to break the
symmetry of the vibrating motion relative to the ground and thus
produce a net translational movement. The antisymmetry elements
are, in general, at an angle to the vibrating surface, which angle
will preferably be other than perpendicular to the vibrating
surface. The elements may consist of bristles, semi-stiff pins,
bumps, or any textured projection. The purpose of these
antisymmetry elements is to convert the symmetrical standing waves
of the vibrating surface into propulsive movements of the device.
Specific examples of such embodiments include, for example,
flexible brush bristles, which are curved backward; small spines or
spicules embedded in a flexible matrix; fins; and a conformable
mat.
In addition to providing translational movement, the antisymmetry
element contributes to a control mechanism whereby changing the
frequency of the harmonic vibratory motion will cause direction of
the device to change. In addition, in other embodiments of the
invention, the vibrating surface may be segmented and/or there
could be more than one source of vibratory energy, so that there
could be translational movement as well as directional control.
There are at least five distinct aspects to the invention:
Translational Motion from Travelling Waves
Traveling waves, which are produced in the vibrating surface, can
obviously produce translational motion as these waves progress from
one end of the device to the other end. By alteration of the
direction of these traveling waves, steering or directional control
can be produced.
Translational Motion from Standing Waves
Vibrations or waves in a solid or liquid medium can be either
standing waves or travelling waves. From everyday experience one
knows that traveling waves, such as ocean waves, can be used to
propel objects such as, for example, boats or surfers. Standing
waves, however, produce only repetitive motion, which does not
result in any net displacement of material, or translational
motion. An example of this would be the standing waves produced on
the string of a musical instrument. If a standing wave is made to
impinge on the ground, there would be no net motion in any
direction since the displacements of the wave tending to produce
motion in one direction would be cancelled out in the next half
cycle by the return motion of the wave in the opposite direction.
However, it is possible to use standing waves to effect net
translational motion if the waves can be coupled to the ground in
antisymmetric way so that a force in one direction
Directional Control using Vibrating Surfaces ("Focusing Surfaces")
which Interact with Obstacles
The essential understanding here is that focusing surfaces which
are concave relative to the obstacle encountered will tend to steer
the device toward the obstacle, while focusing surfaces which are
convex focusing surfaces tend to steer the device away from the
obstacle. This steering ability is enhanced by the vibrating nature
of the basic motion of the device, as the vibrations tend to
re-align the device toward (or away) from the obstacle.
Directional Control Using Eigenmodes
Directional control can be achieved by using certain normal modes
of the vibrating surface. The best combination of normal modes to
produce the ability to turn left or right would be two modes which
are mirror images of one another and which are asymmetric around
the longitudinal axis of the vibrating surface. When the vibrating
surface is equipped with appropriate antisymmetry elements, the
device will turn either to the left or to the right depending on
which normal mode is active. A normal mode ("eigenmode") can be
selected by vibrating the surface at the specific frequency
corresponding to that mode ("eigenfrequency"). The fact that there
is a one to one correspondence between each eigenfrequency and each
normal mode is known from the physics of wave motions and the
solutions of the wave equation.
Embodiments within the scope of the invention include:
(1) a device which propels itself by means of its own vibratory
motion;
(2) a device which can move on a flat surface;
(3) a device which can move on a channeled surface; during one part
of the wave cycle that is not counterbalanced by an equal and
opposite force in the other direction during the next part of the
cycle. This asymmetry is produced by the antisymmetry elements on
the vibrating surface, which are at an angle to the surface.
This translational motion may be used to propel the device on a
flat surface (one surface of contact between device and substrate),
in a walled channel without a roof (three surfaces of contact), in
a hollow tube (contact on all lateral surfaces), and in liquids
either on the surface or submerged.
Wall Climbing Motion
Certain standing waves, particularly those with circular symmetry,
can produce a suction or vacuum effect as the vibrating surface is
lifted away from the surface during one part of the vibratory cycle
and slightly pushed into the surface during another part of the
cycle. When the surface is being accelerated towards the wall, a
slight positive pressure is produced under the plate, which is more
than overcome by the inertial forces, which are pressing the plate
against the wall. The motion of the plate relative toward the wall
may also simultaneously produce some net translational motion. In
the next part of the cycle when the plate is being accelerated away
from the wall, a vacuum is produced under the plate, which tends to
hold it to the wall but now the inertial force tends to pull the
plate away from the wall. A new wall holding effect depends on the
correct balance between the vacuum producing part of the cycle with
the inertial forces, which try to remove the plate from contact
with the wall. If the motion when the plate is being accelerated
away from the wall is not too violent, there will be production of
a vacuum between the plate and the wall, which will more than
compensate for the inertial force, which tends to throw the plate
away from the wall.
(4) a device which can move by adhering to a wall or other vertical
or slanted surface;
(5) a device which can move by adhering to a ceiling or other
horizontal surface;
(6) a device which uses a vibrational source to create standing
waves in the device;
(7) a device which uses a vibrational source to create traveling
waves in the device;
(8) a device which uses "antisymmetry" texturing of the vibrating
surface to effect translational motion from standing waves; and
(9) a device which can use a balance of inertial and suction forces
to adhere to a wall or ceiling and also translate (move) along that
wall or ceiling.
In another embodiment of the invention, the vibration-producing
element of the device comprises an electromechanical buzzer, a
rotating eccentric cam on an electric motor, an escaping gas which
vibrates a reed, an element which produces standing waves in the
device, an element which produces traveling waves in the device, a
device wherein standing (stationary) waves can produce
translational motion by means of elements at an angle to the
vibrating surface of the device, or a combination of two or more
thereof, or the functional equivalent of one or more thereof.
Antisymmetry elements, as discussed above, produce a net force in
one direction when averaged over the entire vibratory cycle. Such
elements may be, for example, bristles, periodic elevations,
regular or irregular projections, or conformable surfaces.
A device according to the invention can be controlled or steered by
means of special surfaces called "focussing surfaces", by means of
varying the frequency of vibration to select a particular
eigenmode, by means of selective damping of the vibrating plate at
a nodal line of a desired eigenmode in the case of a standing wave
vibrational-source, by changing the direction of rotation of the
vibrating device in the case of traveling waves.
The invention can perhaps be better appreciated by making reference
to the drawings. FIG. 1 represents an embodiment of the invention
which comprises a circular substrate 10 having a source of
vibratory harmonic motion or motor 12 centered thereon. Adjacent
motor 12 is a battery holder 14 containing two AA batteries 18. Two
wires 20 lead from battery holder 14 to a switch 22, which switch
22 is electrically connected through wires 24 to motor 12.
Activating switch 22 closes the electrical circuit comprising
batteries 18 and motor 12 and causes motor 12 to vibrate.
Motor 12 can comprise any known or future source for imparting
vibrational energy, to cause harmonic motion. Motor 12 has to be
sufficiently small and efficient to impart vibrational energy but
not weigh too much that it negates the vibrational effect or causes
the device to slide or fall off a non-horizontal surface. A
representative motor 12 is a commercially available pager motor,
which provides vibration in the frequency of from about 5 to 20
cycles per second.
Substrate 10 should be a flexible but rigid surface that can
vibrate in response to the vibrations from motor 12. Typical
materials useful for substrate 10 include polymers, metal,
ceramics, and the like. Substrate 10 should be thick enough to
support motor 12 but thin enough to vibrate.
Substrate 10 can be of almost any shape or size, dependent upon the
strength or power of motor 12. The weight of motor 12 plus the
batteries would also be a factor. The bottom surface 30 of
substrate 10 is preferably substantially flat, although a slightly
concave or pie-plate or FRISBE-shape surface will work as well.
FIG. 2 is a cross-sectional view of the device shown in FIG. 1 in
position on a vertical surface 32. With the motor 12 activated, the
device 34 will either remain in approximately one position, or it
may slowly move in a direction along surface 32. If an external
lateral force is applied to motor 12 or substrate 10, device 34
will tend to go in that direction. Also, device 34 may be
configured as discussed above so that vibratory action may result
in directional control.
FIG. 3 is a schematic view of an embodiment of the invention where
the device 40 comprises a housing 42 containing a vibrational
energy source (not shown specifically) and a power supply (not
shown specifically), such as one or more batteries, and a substrate
44. Extending from the lower surface 48 of substrate 44 are
bristles 50, which are shown at an angle of about 30.degree. from
normal to horizontal surface 52. Preferably bristles such as
bristles 50 will be from about 45 to 85.degree. from normal.
Optionally bristles 50 could be slightly curved and are preferably
comprised of a suitable flexible polymeric material.
EXAMPLES
Example 1
The device comprises a Styrofoam pie plate (9 inches in diameter,
of central depth 3/4 inch, with an edge at the circumference of
width approximately one-half inch), an electrical motor with an
eccentric weight, and 2 Ni--Cd batteries (AAA size). The motor and
batteries are placed on the underside of the pie plate.
In one use, the device, with the pie plate upside down, translated
with the circumferential edge in contact with a surface. This
device translated in a vertical direction along a wall, in an
embodiment termed "wall crawling pie plate."
In another use, the motor and batteries can be placed in an
enclosure, such as a film can. The device, with the pie plate
upside down, translated with the circumferential edge in contact
with a surface. Specifically, the device can translate along a
surface, such as a porcelain tub surface, underneath water.
Example 2
The device comprises an approximately flat 3 inch diameter,
approximately 1 mm thick, circle or approximate circle of material
(which can be cut, for example, from the bottom of the 9'' diameter
Styrofoam pie plate), a pager motor, and a power source. The power
source can be wires connected to the motor which lead to a battery
remote from the 3 inch diameter circle.
On energizing the motor and creating vibrations, the device
translated along a surface.
Example 3
The device comprises a ping pong ball with a hole, a motor, and a
power source. The motor and power source can be placed within the
ping pong ball. On energizing the motor and creating vibrations,
the device spins when placed in a cup of water. It is believed that
this is through rotational traveling waves.
Example 4
The device comprises a foam wheel with a motor and a power source.
On energizing the motor and creating vibrations, the foam wheel
revolved.
Example 5
The device comprises a piece of scrub brush with a motor and a
power source. The motor is attached to the portion of the scrub
brush opposite the bristles. On energizing the motor and creating
vibrations, the scrub brush moved forward.
Example 6
The device comprises a motor, potted in a container, with a power
source or leads to a power source, wherein bristles are attached to
the scrub brush. This device climbed vertically in a cardboard tube
even carrying its own battery.
Example 7
The device comprises a motor with a power supply, a brass sheet,
and bristles attached to the brass sheet on the side opposite to
the side with the motor. Depending on the frequency of the motor,
the device, when placed on a surface, turned left, turned right, or
went straight ahead. The bristles are used to break symmetry.
The preceding specific embodiments are illustrative of the practice
of the invention. It is to be understood, however, that other
expedients known to those skilled in the art or disclosed herein,
may be employed without departing from the spirit of the invention
or the scope of the appended claims.
* * * * *